The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to treat a patient's skin and subcutaneous tissue, including skin resurfacing procedures, the removal of pigmentations, vascular lesions, scars and tattoos, hair removal and/or transplant procedures, treatment of skin cancer, skin rejuvenation (e.g., wrinkle removal), liposuction, blepharoplasty and the like.
In early dermatology procedures, cosmetic surgeons often employed chemical peels and/or dermabrasion techniques to remove outer layers of the patient's skin to rejuvenate wrinkled skin or to remove skins disorders, such as acne, lesions, early skin cancer, etc. These dermabrasion and chemical procedures, however, are difficult to control, requiring great surgical skill. In addition, these somewhat inelegant techniques often cause excessive bleeding, collateral tissue damage and patient discomfort.
In an effort to overcome some of the limitations of dermabrasion and chemical peels, lasers have been developed for use in cosmetic surgery. Lasers have improved the accuracy of skin resurfacing procedures, and they have reduced collateral damage to the tissue surrounding and underlying the treatment site. In laser dermatology applications, a handpiece is typically used to guide the output of a laser to the patient's skin, and to form a laser spot of a desired size on the region of the skin which is to be treated. The handpiece is typically attached to one end of an articulated arm which transmits the output of a medical laser (such as CO.sub.2 or Er: YAG lasers) to the handpiece and allows the handpiece a wide range of motion.
Although initially promising, lasers suffer from a number of drawbacks in dermatology procedures. In the first place, laser equipment can be very expensive because of the costs associated with the laser light sources. Moreover, those lasers which permit acceptable depths of necrosis (such as excimer lasers, erbium:YAG lasers, and the like) provide a very low volumetric ablation rate, requiring numerous passes over the same treatment area which amounts to longer procedural times. In addition, erbium:YAG lasers generally do not provide effective hemostasis during the procedure, resulting in excessive bleeding which disrupts the surgeon's view of the treatment site. The CO.sub.2 lasers provide a higher rate of ablation and an increased depth of tissue necrosis than their erbium: YAG counterparts. On the other hand, CO.sub.2 lasers often create significant residual thermal injury to tissue at and surrounding the treatment site, which requires long healing periods for the patient. In addition, CO.sub.2 lasers are associated with much pain and, therefore, require a lot of anesthesia, which increases the cost and length of the procedure.
In the treatment of vascular lesions, lasers are used to irradiate the surface of the skin. The laser energy penetrates through the skin and is absorbed in the blood, which coagulates and collapses the vein. Unfortunately, there are also problems associated with the use of lasers in these procedures. For example, although most of the laser energy passes through the tissue to the vessel, scattering and absorption of the light take place in the tissue. This absorption can cause significant changes in skin coloration and even scarring.
Monopolar electrosurgical instruments have been used to effect electrodessication of abnormalities, such as lesions, skin tags, viral warts, pigment nevi, moles and skin cancer. For example, Conmed Corporation manufacturers a monopolar device, termed the Hyfrecator.TM. having a single active electrode at the tip of an electrosurgical probe. In these procedures, the skin abnormality is typically removed with a scalpel, and a low voltage is applied to the active electrode in contact with the target tissue to deliver electric current through the tissue and the patient to a dispersive pad or indifferent electrode. The voltage desiccates the remaining abnormal tissue, and coagulates severed blood vessels at the target site. The remaining tissue is then removed with a sponge or similar material. The voltage generally must be low enough to prevent charring and potential scarring of the underlying dermis.
The present invention is particularly concerned with treating "baggy eyelids" deformity, a condition that can result in both functional and cosmetic problems. Baggy eyelids can be caused by a variety of conditions, such as blepharochalasis (laxity and sagging of the upper eyelid), dermatochalasis (loss of skin elasticity in the upper eyelid), hypertrophy of the orbicularis muscle, protrusion of intraorbit fat and lateral fullness of the upper eye. Surgical treatment for baggy eyelids, known as blepharoplasty, typically involves the creation of a linear or crescent shaped incision across the upper or lower eyelid so that a portion of the patient's skin can be folded over to expose the underlying orbital septum. The orbital septum is then opened to expose the underlying fat tissue, and the desired amount of fat tissue is excised from the patient.
The dermal incisions required to expose underlying fatty tissue are typically created with a variety of convention resection devices, such as a scalpel or laser. While generally effective, these devices each have one or more drawbacks. The scalpel requires additional hemostasis, and often leads to postoperative pain and relatively long healing periods. Lasers typically effect simultaneous hemostasis as they deliver thermal energy to the target area. However, this thermal energy also leads to excess healing time and postoperative pain. In addition, the amount of thermal energy required by these devices may sufficient damage the target site to leave a permanent scar on the patient.
RF energy has been used to remove or otherwise treat tissue in open and endoscopic procedures since they generally reduce patient bleeding associated with tissue cutting operations and improve the surgeon's visibility. In procedures for treating baggy eyelids, monopolar RF devices, e.g., the Colorado Needle.TM., are frequently used to create the necessary incisions in the patient's eyelids. These electrosurgical devices and procedures, however, suffer from a number of disadvantages. For example, conventional electrosurgical cutting devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue. At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue. This high current density causes cellular fluids to rapidly vaporize into steam, thereby producing a "cutting effect" along the pathway of localized tissue heating. This cutting effect generally results in the production of smoke, or an electrosurgical plume, which can spread bacterial or viral particles from the tissue to the surgical team or to other portions of the patient's body. In addition, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.